This dissertation is concerned with ultra-precision profile measurement of aspheric surfaces using contact probing technique. A contact probe has been designed as a sensing device to obtain measuring resolutions in nanometer regime utilizing a leaf spring mechanism and a capacitive-type sensor. The contact probe is attached on the z-axis during measurement while aspheric objects are supported on an precision xy-stage whose lateral motions are monitored by a set of two orthogonal plane mirror type laser interferometers.
Experimental results show that the contact probing technique developed in this investigation is capable of providing a repeatability of 50 nanometers with a ±3σ uncertainty of 300 nanometers. Thermal disturbance is found the most significant factor that should be precisely controlled for accurate measurement. A special registration algorithm has been prepared and used for comparing measured data with design data so that form errors of measured aspheric surfaces are precisely identified.
